This report examines and describes the general nature of air flow disturbances created by structures such as offshore platforms. It relies on wind tunnel model tests for its basic information, but account has been taken of experiences gained at full scale in establishing their relevance.

The flow patterns have been described in terms of basic elements of separated turbulent flow, with the object of enabling a designer to estimate sensibly the effects of particular configurations. As a result general rules for helideck location are derived and summarised in sections 5 and 7

Examples of particular configurations and module dispositions are given to illustrate the main theme and to point to potentially sensitive areas.

It is concluded that the overall wind influence on a projected installation can be assessed from these results, but that questions of detail may still require wind tunnel investigation of the particular model. This remains the only method to check out marginal cases and to explore the sensitivity of broadly satisfactory flows to the disposition of specific smaller elements, such as cranes, flare booms, walkways and similar obstructions.